Automatic telephone-exchange system.



C. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC-12.1914.

l 1 88,929 Patented June 27, 1916.

3 SHEETS-SHEET I.

WIT/726686: //7ve/17'0/ 9w. C/96II/M6L. g'aoa/rum. QE WW W 4/7 C. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC-12,1914.

Patented June 27, 1916.

3 SHEETS-SHEET 2- T W/fnesses: five/en far.

M&. Char/es L. Gwarum 2 g m C. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC- 12. m4.

1 9 1 ,Q9. Patented J 11116 27, 1916.

3 SHEETS-SHEET 3- Vifi'inessasx Mveruar: @9791, M2 WWW/e5 L. Gaaa'um STATES PATENT @FJFKGE.

CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, T0 WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION NEW YORK.

Specification of Letters Patent.

Patented June 2'3, 191%.

Application filed December 12, 191 4. Serial No. 876,837.

To all whom it may concern Be it known that I, CHARLES L. GOODRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have inventedcertain new and useful Improvements in Automatic Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to an automatic telephone exchange system and more particularly to a satellite. exchange system or the like.

The object of the invention is to economize in the use of trunk lines between the satellites and the main exchange ofiices without the necessity of variable manipulation of the subscribers calling devices to discriminate between calls local to the satellite and calls requiring connection through a main office. To this end automatic discriminating means are provided which operate without the necessity of any knowledge on the part of the calling subscriber whether the wanted subscriber is connected to the same satellite as the calling subscriber or to a main oifice, the subscribers calling device being manipulated in every instance in the same manner and in accordance with the telephone number of the subscriber wanted.

In its preferred embodiment, the invention provides an interofiice trunk finder which is connected to the line finder and also a local trunk finder which finds the circuit connecting the line finder and the interofiice trunk finder. To the local trunk finder are connected a local selector and a test switch.

the connection is completed over the trunk to the central ofiice. The invention will be more readily understood by reference to the accompanying drawings in which Figure 1 is a diagrammatic illustration of a system embodying the invention, and Figs.

2 and 3, when placed end to end with Fig. 3 at the right of Fig. 2, illustrate the circuitsand apparatus of the system.

In Fig. 1, the diaphragms inclosed in the square S represent apparatus at the satellite office, and the diagrams inclosed. in the square M represent apparatus at the main oflice. The latter apparatus may be of any sultable, well-known type, operating in the usual manner, and hence further descriptIon thereof is unnecessary.

A represents a calling subscribers station, the telephone line therefrom extending to the line finder B.

X represents a wanted subscribers station which is within the same satellite as the calling subscriber A, the telephone line of station X being shown as extending to the finder B, though it obviously may extend to some other finder of the same satellite ofiice, if the calling and the wanted subscriber are in diiferent hundreds of the same satellite.

Y represents a subscribers station which is not connected to the satellite office S, and which must therefore be reached by the calling subscriber over the trunk line between the satellite oflice S and the main oflice M.

The line finder B is connected to the brushes of an interofiice trunk finder C, through which the calling subscribers line is adapted to be connected, to an idle trunk line to the main otlice. The line finder, in

addition to connecting the telephone line to the interofiice trunk finder, also connects it to the contacts of a local trunk finder I), there being a circuit connecting the brushes of the interoflice trunk finder and the brush contacts of the local finder. The brushes of the local trunk finder D are connected to a local selector E and also to a test switch F having a single brush contact, that is to say each local trunk has associated therewith a local selector E and a test switch F.

When a call is originated, the line finder B finds the calling line, and the interoffice trunk finder C finds an idle trunk to the central oflice. At the same time, the finder switch D finds the circuit which connects. the line finder and the trunk finder. If the connection is for some line X within the satellite, the test switch F causes the release of the trunk finder C so that the trunk appropriated thereby may be used for other connections, and the connection is completed through the local selector E and a local 110 connector G. If, on the contrary, the call is for a line not connected to the satellite,

the test switch F causes the. finder D and its associated switches to be released and the connection is established over the trunk to the central oflice.

The several switches may comprise any suitable mechanisms, those illustrated in the drawings being of a well-known type.

Any further description of the apparatus believed to be necessary to an understanding of the invention, will be given in connection with a description of the operation of the system, which will now be set forth.

Let it be assumed that the subscriber at station A of a satellite is calling a subscriber connected either to the same satellite or to some other ofiice. "The calling subscriber at station A removes his receiver from the test relay 11 of line finder B, as follows:

from grounded battery through relay 11, brush 10, contacts 9 and 8 to ground. Relay 11 thereupon closes its contacts 12 and 13. In closing. its contact 12, the relay 11 closes a locking circuit for itself through brush 14 of the line finder. The closure of contact 13 completes a circuit for the motor magnet 15 of the line finder and the escape magnet 16. The escape magnet is thus prepared to advance the side switches 17, 18, 19 and 20 of the line finder to the second position when the brushes of the line. finder find the calling line.

The motor magnet 15 being energized in the manner described interrupts its own circuit at contact 27, thereby moving the brushes 10, 14, 21 and 22 of the line finder step-by-step over the line finder contacts. When the brushes of the line finder arrive at the contacts representing the calling line, the brush 14 is on a contact from which ground has been removed by the opening of contact 23 of relay 1. The circuit of relay 11 being thereby opened, contact 13 in the circuit of the motor magnet 15 and of the escape magnet 16 is opened. The resulting deenergization of the motor magnet 15 leaves the brushes-of the line finder at rest upon the contacts of the calling line, and the deenergization of escape magnet 16 causes the side switches 17 1'8, 19 and 20 to move to the second position. The side switch 19, in its second position, places ground upon the cutoff relay 4, which, thereby becoming energized, opens its back contacts 3 and 7 and connects the telephone line 5, 6 through the front contacts 24 and 25 of relay 4 to .the contacts of line finder B. The telephone line is thus connectedto the brushes 21 and 22 of the line finder. The line relay 1, becoming deenergized by the openingof back contact 3 of relay 4, places ground through contact 23 upon the line finder contact on which the brush 14 rests, thereby rendering the line busy against any other switch.

At the same time that the operating circuits for the line finder B were established in the manner just described, similar operating circuits were established for the trunk finder C, as will now be described. When the line relay 1 was energized and closed its contact 8, a circuit was completed for the test relay 126 of thetrunk finder C, as. follows: from grounded battery, through test relay 26, brush 28 of the, trunk finder, side switch 20 of the line finder, contact 8, to ground. The test relay 26 responds, closing its contacts 29 and 30. The contact 29 is in a locking circuit for the relay 26 through the brush 31. of the trunk finder. The closure of contact 30 completes a circuit for the motor magnet 32 and also for the escape magnet 33. The energization of the motor magnet 32 causes the brushes 31, 28, 34 and 35 of the trunk finder to move step by step until they reach the contacts of an idle trunk 36, 37 which extends to the central ofiice. The brush 31 then fails to find ground and the circuit for the relay 26 is opened, thereby opening the'circuit of the motor magnet 32 and the escape magnet 33. Thebrushes of the trunk finder C are thus brought to rest and the side switches 38 and 39 are moved to their second position. The

side switches 17, 18 of the line finder B and the side switches 38 and 39 of the. trunk finder C being now in their second position, the telephone line is extended over the idle trunk line 36, 37. to the central ofiice.

The movement of the side switches 17 and 18 to their second position also extends the subscribers telephone line to contacts on the local trunk finder D, and -closes circuits which result in the movement of the brushes 40, 41, 42 and 43 of the finder to select the contacts to which the line is extended. The circuit for the starting relay 44 which controls the establishment of the circuits for the motor magnet 45 of the trunk finder D is as follows: from grounded battery, through starting relay 44, contact 46, side switches and 17, brush 22 ofthe line finder B, contact 24 of relay 4, telephone line 5, 6, contact 25, brush 21, side switch 18, stepping relay 47, to ground. The resultant energization of the starting relay 44, places ground on. its front contact 48. Through this grounded contact 48 the brush 41 of finder D and side switch 53 a circuit is closed for the test relay 49, which thereby closes a locking circuitfor itself through its front contact 50 and brush40 of the finder switch D. Through its front contact 51 the relay 49 closes a circuit for the motor magnet 45 and the esca e magnet 52 of the finder D. The brushes 0, 41, 42 and 43 of the finder D then move. step by step until they reach the contacts to which the telephone line has been extended. The above. mentioneG. locking circuit for relay 49 is then open at back contact'58 of the starting relay 44. The resultant deiinergization of relay 49 and the opening of its contact 51. opens the circuit of the motor magnet 45 and escape magnet 52. The escape magnet thereupon causes the side switches 53, 54 and 55 to move to their second position. The side switch 53 completes a circuit to ground for the relay 56 and the escape magnet 57. The relay 56 thereupon opens its contact 46, thereby opening the circuit of the starting relay 44. The resultant closure of the back contact-58 of relay 44 places ground upon the terminal on which brush 41 of finder D is resting, thereby rendering the line busy.

The above mentioned energization of the escape magnet 57 is for the purpose of placing said magnet in readiness to advance the side switches 59, 60 and 61 to their second position, as will hereinafter be described.

The side switches'54 and 55extend the connection of the calling line to a stepping relay 62. Therefore when the calling subscriber operates his dial 63 in making a call, both the stepping magnet 47 and the step-- ping magnet'62 receive impulses of current. The stepping magnet 47 by opening and closing its contact 64 interruptsthe circuit of the trunk line 36, 37 and causes the operation of the selector at the exchange (not shown). 1 Meanwhile the stepping relay 62 controls the operation of the local selector E and the test switch -F in the manner now to be described.

Upon relay 62- being connected to the line I its contact 67, 68 closed, while th'e impulses of current are being sent over the line by the operation of the subscribers calling dlal 63. The impulses of current through the relay 62 interrupt acircuit from ground,

through contact 69 of the relay 62, contact 67 of relay 66, side switch 74, motor magnet 70 of the special switch F, and also motor magnet 71 of the local selector E. A slowacting relay-72 also has its circuit closed through contacts 67 and 69, thereby energizing an escape magnet 73 which controls side switches 74,75, 76 and 77, and also energizing an escape magnet 78, which controls side switches 79, 80, 81 nd 82. In response to the first movement of the dial 63, the motor magnets 70 and 71 elevate, respectively, the-brush 83 of the test switch F and the brushes 84, 85 and 86 of the local selector 1 E. At the end of the first operation of the dial, the slow-acting relay 72 is deiinergized by the opening of contact 69 of the steping relay 62, and the escape magnets 73 and 8 become deenergized. The side switches 74, 75, 76 and 77 controlled by the escape magnet 73 and the side switches 79, 80, 81

sent by the next movement of the dial, the

rotary magnet 87 of the test switch responds, but the rotary magnet 88 of the local connector E does not respond, since its circuit can only be closed in. the third position of the side switch 76' of the test switch F.

The brush contacts of the test switch F may be and preferably are arranged in hori-.

zontal rows (ten in number but two only of which appear in the drawing) successively reached by the action of the vertical magnet 70. A. certain one of these contacts, for example contact 89, the position of which requires it to be reached by vertical and rotary steps, the numbers of which correspond which includes the calling line, has a connection the function of which is to release theinteroflice finder switch C, while permitting the call to be completed locally. Another such contact or contacts like 89 would have a like connection or like connections ifthe satellite has more than the while permitting the call to be extended to the distant subscriber wanted through an interoflice "trunk.

When the second set of pulses are sent by the subscriber operating his dial 63, the circuit hereinbefore described for the escape magnet 73 is again established and a circuit is also established for the'rotary magnet 87 of the test switch F, as follows: from grolmded battery, through magnet 87, switch 4 in its second position, and cont-acts 67 and 69' to ground. The brush 83 is thereby rotated over the contacts of the level to which the brush had been elevated by the previous operation of the dial. At the end of its rotation the brush 83 will rest either upon a contact such as 89 that will result in the release of the trunk connection or upon a contact such as 113 that will release the local apparatus, dependent upon whether or not the wanted subscriber is connected to the same satellite as the calling subscriber.

In the drawing the contact 89 of the test switch F represents a certain hundred of the same satellite as that of the calling subscriber, and all of the other contacts of said switch F represent hundreds which are not in that satellite. If it be assumed that the brush 83 stops upon one of the contacts such as 113 which does not represent a hundred of the satellite, circuits are established for releasing the local apparatus. The circuit through the brush 83, in such case, is as follows: from ground, through the side switch 77 (the side switches controlled by the escape magnet 73 having moved to the third position), brush 83, contact 113, contact 68 of the slow-release relay 66 and release magnets 97 of .finder D, 98 of test switch F and 99 of local selector E, to grounded battery. The switches D, F and E are therefore restored to normal. The restoration of the side switch 53 of finder D to its normal position opens the circuit of the escape magnet 56, the circuit of which was closed preparatory to operating the side switches 59, 60 and 61, as hereinbefore described. .These side switches are thus operated and the connection of the line to the local finder is thereby broken. The line is thus disconnected from the switches D,. E and F, and the completion of the call is made in the usual manner over the trunk line 36, 37 which leads. to the central oflice.

If, on the contrary, it be assumed that the brush 83 of the test switch F stops upon a contact such as 89, representing a, certain hundred of the satellite,thetrunkconnection to the main exchange is released, the circuit for such release being established through contact 89 of the switch F, as follows: from grounded battery, through relay 90, contact 89, brush 83 to ground through side switch 7 7, the side switches controlled by the escape magnet 73 having moved to their third position. The relay 90 is energized, closing its contact 91, thereby placing interrupted current on a low resistance release relay 92, the circuit of which is as follows: from grounded battery, through interrupter 93, contact 91 of relay 90, back contact 94 of relay 49, finder brush 40, release relay 92, back contact 58 of relay 44, to ground. The release relay 92 operating closes its front contact, thereby completing a circuit for the trunk release magnet 96, thus releasing the trunk finder.

The side switches of the test switch F being now in the third position and the side switches of the selector E being in the second position, a circuit is established for the rotary magnet 88 of selector E, as follows: from grounded battery, through magnet 88, side switch 80 in its second position, side switch 76 in its third position to ground. This causes the brushes 84, 85 and 86 of local selector D to hunt for a local trunk 100 toan idle connector. As soon as the brushes find such trunk, the escape magnet 78 causes the sideswitches 79, 80, 81 and 82 of selector E to move to the third position. This breaks the circuit of the rotary magnet 88 at side switch 80, thereby stopping the brushes 84, 85 and 86 upon the contacts of the trunk 100. The circuit of the escape magnet 78 is also opened at side switch 79,

thereby causing the side switches 79, 80, 81

and 82 to move to the third position. The calling line is thus extended through side switches 81 and 82, brushes 84 and 85, and the local trunk to the local connector. Therefore, impulses of current sent over the line by the continued manipulation by the calling subscriber of his dial 63 are transmitted to operate the local connector and the con nection to the wanted subscriber completed in the usual-manner.

When the calling subscriber at station A hangs up his receiver, battery is supplied from the connector circuit in the well known way, to a low resistance release relay 101, through the brush 86 of selector E and side switch 79, now in the third position. The energization of relay 101 closes circuit for the release of the several switches, as follows: from ground, through contact 102 of relay 101, release magnet 97 of finder D to grounded battery, and also through the release magnets 98 and 99, of switches F and E, respectively, to grounded battery. These magnets, therefore, operate to restore their respective switches D, F and E to normal position. Circuits are also established for release magnet 103 of the line finder B and the release magnet 104 of the side'switches 59, 60 and 61, as will now be described. During the time that the line was in use, slow-release relays 105 and 106 were energized, the circuit for relay 106 being closed through contact 107 of the stepping relay 47, andthe circuit for relay 105 being closed through front contact 108 of relay 106. Also when the calling subscriber hangs up his receiver relays 106 and 105 are successively deenergized by the opening of contact 107 and a momentary ground is placed upon the release magnets 103 and 104 through contacts 109 and 110. The release magnets 103 and 104 therefore operate to restore their respective switches to normal position. In case the connection had been through the trunk finder C a circuit .--is established in like manner for its release magnet 96, through contacts 111 and 112 of relays 106 and 105, respectively, upon the subscriber at station A hanging up his receiver.

While, in the system herein specifically described, the invention is disclosed as applied to a satellite exchange system, it is obvious that the invention is adapted to other applications as, for example, discriminating between groups of subscribers lines at the same ofiice. It should, therefore, be understood that the invention is not necessarily limited to'the satellite exchange system shown and" described herein.

\Vhat is claimed is:

- 1. In an automatic telephone exchange system, a satellite oflice, an interofiice trunk finder, a local trunk finder, automatic switching mechanism for simultaneously connecting a calling line to the inter-oflice trunk finder and the local trunk finder, and

automatically operating means, operative during the progress of the call, for releasing the local trunk finder whenthe wanted subscriber is not within the satellite and for releasing the interofiice trunk finder when the wanted subscriber is within the satelite.

2. In an automatic telephone exchange system, a main ofiice, a. satellite office, interoffice trunk lines from said satellite to said main of fice, interoflice trunk finders, local trunk lines at said satellite oflice, local trunk finders, automatic switching mechanism for simultaneously connecting a calling line to an interoflice trunk finder and a local trunk finder, a test switch connected to the local trunk finder, and automatically operating means controlled by said test switch for releasing the local trunk finder when the wanted subscriber is not within the satellite and for releasing the interoflice trunk finder when the wanted subscriber is within the satellite.

3. In an automatic telephone exchange system, a satellite oflice, a line finder, an'inscriber is not within the satellite, and for releasing the interoflice trunk finder when the wa'ntedsubscriber is within the satellite.

4. In an automatic telephone exchange system, a satellite ofiice, an interofiice trunk finder and a local trunk finder having a circuit connectin the brushes of the former with one set 0 brush contacts of the latter, automatic switching mechanism for connectin a calling line to said circuit of the intero ce trunk finder and the local trunk finder, and automatically operating means, operative during the progress of the call, for releasing the local trunk finder when the wanted subscriber is not within the satellite and for releasing'the interofiice trunk finder when the wanted subscriber is within finder and a local trunk finder having a circuit connecting the brushes of one of said finders with the brush contacts of the other of said finders, a testswitch connected to said local trunk finder, and automatically operating means controlled by said test switch for releasing the local trunk finder when the wanted subscriber is not within the satellite and for releasing the interofiice trunk finder when the wanted subscriber is within the satellite.

6. In an automatic telephone exchange system, a satellite oflice, an interoffice trunk finder and a local trunk finder having a circuit connecting the brushes of the former with one set of brush contacts of the latter, a test switch connected to the brushes of said local trunk finder, and automatically operating means controlled by said test switch for releasing the local trunk finder when the wanted subscriber is not within the satellite and for releasing the interofiice trunk finder when the wanted subscriber is within the satellite.

7( In a telephone exchange system, a main office, a satellite ofiice, interofiice trunk lines from said satellite to said main oflice, local trunk lines. at said satellite, automatic switching mechanism at said main exchange and at said satellite for effecting connection between subscribers; a test switch associated with each local trunk line, means whereby the first series of selective impulses will effect the simultaneous actuation of the test switch and of the connection effecting switching mechanism at said main exchange and at said satelllte, and the second series of selective impulses will effect the simul taneous actuation of the test switch the switching mechanism at said main change, and means operated under the e ontrol of said test switch for returning" said main office switching mechanism to normal when thewanted subscriber is within the satellite and for returning said satellite switching mechanism to normal when the 'wanted subscriber is not within the satellite.

' 8. In a sectional telephone exchange sys- 9. In a sectional telephone exchange system, subscribers lines terminating in different sections thereof, an inte'rsectional trunk finder, a local trunk finder, automatic switching mechanism for simultaneously connecting a calling line to the said intersectional trunk finder and the said local trunk finder, and automatically operating means, operative during the 'ogress of the call, for releasing thedoica trunk finder when the wanted subscriber is not within the section in which the calling line terminates and for releasing the intersectional trunk finder when the Wanted subscriber is within said section.

In witness whereof, I hereunto subscribe my name this 11th day of December, A. D.

CHARLES L. GOODRUM. \Vitnesses E. EDLER, K. L. STAI-IL. 

